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When to Plant Rue in Caldwell County, TX

Caldwell County, Texas Zone 9a May

What to do in May

We've pulled the most time-sensitive tasks for Caldwell County, Texas this May and put them front and centre. Tackle them in order.

Avg. last frost February 27
Avg. first frost December 1
Soil temp (4") 66°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Start harvesting rue

    If you can't use it all right away, check the food-preservation section of your planner.

A few tasks this May that'll pay off in June
  • First harvests: rue

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Rue is a bitter, aromatic perennial herb with bluish-green foliage used historically in medicine and as a pest deterrent. Handle with care as its sap can cause skin irritation.

Caldwell County, Texas is in USDA Zone 9a. The average last spring frost is February 27 and the first fall frost is December 1, giving you a growing season of approximately 277 days.

At an elevation of 3,482 feet, Caldwell County receives approximately 60.8 inches of rainfall annually with predominantly clay soil. Summer highs average 90°F, providing good warmth for Rue during the growing season. Clay soil retains moisture well for Rue, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Rue root diseases.

Caldwell County, TX (Zone 9a) Year-round
277 days
Last Spring Frost February 27
277 growing days
First Fall Frost December 1

Caldwell County Soil Profile

Soil Type

Clay

Soil pH

6.8-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (139 days to spare)
Transplant: Feb 20 🍅 Harvest: May 1 – Jul 3
Recommended (50%) ✓ Fits season (137 days to spare)
Transplant: Mar 6 🍅 Harvest: May 15 – Jul 17
Safe Start (90%) ✓ Fits season (126 days to spare)
Transplant: Mar 29 🍅 Harvest: Jun 7 – Aug 9

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Caldwell County

How your county's soil matches Rue's growing requirements.

Soil pH

Your soil pH (6.8–8.1) overlaps with Rue's range (6.0–7.5), though not a perfect match.

Soil Texture

Heavy clay soil (43% clay) in Caldwell County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Rue.

How to Plant Rue

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Rue

4
successive plantings in your 277-day season

Sow every 8 weeks. Last sowing by Sep 02 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Rue

Rue needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Rue Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 2.2" 2.1" 0.1" 💧 Light watering
Mar 2.2" 4.1" 0" ✅ Rainfall sufficient
Apr 2.2" 6" 0" ✅ Rainfall sufficient
May 2.2" 9.9" 0" ✅ Rainfall sufficient
Jun 2.2" 9.2" 0" ✅ Rainfall sufficient
Jul 2.2" 7.5" 0" ✅ Rainfall sufficient
Aug 2.2" 7.9" 0" ✅ Rainfall sufficient
Sep 2.2" 5.6" 0" ✅ Rainfall sufficient
Oct 2.2" 3.8" 0" ✅ Rainfall sufficient
Nov 2.2" 1.8" 0.4" 💧 Light watering
Dec 2.2" 1.5" 0.7" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Caldwell County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Rue Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Rue needs ~1,400 GDD — county provides 4,865 GDD Excellent fit

Rue Planting Timeline — Caldwell County, TX

Rue Planting Calendar

Activity When Date Range
Transplant Outdoors March 6 Mar 6 – Mar 20
Harvest May 15 May 15 – Jul 17

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March Transplant Outdoors
April
May Harvest
June Harvest
July Harvest
August
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

277 days in Caldwell County

Growing Tips for Rue in Caldwell County

Direct sow Rue outdoors after February 27 in Caldwell County when soil has warmed and frost danger has passed.

With Caldwell County's clay soil (43% clay), work in 3-4 inches of compost before planting Rue. Avoid tilling when soil is wet to prevent compaction.

General growing tips

Start seeds indoors or direct sow. Plant in well-drained soil. Wear gloves when handling as sap can cause phytophotodermatitis. Prune in early spring.

Companion Planting

Good Companions

Avoid Planting Near

  • Basil
  • Sage

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Rue in Caldwell County, TX?

Caldwell County is in Zone 9a with an average last frost of February 27. Plan your Rue planting based on this frost date — see the calendar above for exact timing.

What planting zone is Caldwell County, TX?

Caldwell County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 27 and first fall frost is December 1.

🌱

Your Caldwell County Garden Planner — Free

A 24-page printable planner built for Caldwell County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Caldwell County, TX. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.